HISTOLOGY: MICROBIOLOGY: SKIN: General Series on HIV Infection and AIDS. Skin biopsy of Kaposis sarcoma.; Skin biopsy of Kaposis sarcoma, high magnification. Two characteristics of Kaposis sarcoma are extravasated erythrocytes and deposits of hemosiderin. Contributed by Jonathan W. M. Gold, M.D., Cornell University Medical College, New Yor